Backing for stencil sheets



Patented Nov. 4, 1930 snznnno HORII, or TOKYO, JAPAN BACKING FOR STENCIL SHEETS No Drawing. Application filed February 21, 1928, Serial No. 256,061, and in Japan January 23, 1928.

posed stencil sheet. In that case, the characters cut upon the stencil sheet are more visi ble to the typist. And again, the face of the backing sheet is most eflicient as an'extractor, the small particles of wax expressed from the fibers of the base of the stencil sheet by the impact of the type clinging to such printed backing sheet.

It has also been proposed to provide a backing sheet of firm-paper having a varnished surface, which serves the double purpose of making the sheetimpervious to moisture and of acting as an adhesive for the purpose of binding a softabsorbent paper firmly thereto.

Thebacking sheet, in accordancewith the present invention, consists of a firm paper lmpregnatedwith a coating material chiefly consisting of non-drying oil, e. g., castor oil, or a similar oil, either with or without a hardening material, such as waxes or resins.

While this backing sheet may be used in combination with any kind of stencil (sheet, it is most suitable for use with the so-called dryprocess stencil sheet which has a coating including a gelatinous organic colloid, such as gelatine, or esters of polysaccharides, dispen'sed with an olea'ginous softening material.

It has been found that a backing sheet which has a coating of drying oils or varnishes, as above referred to, has a certain disadvantage in that the coating is not stable and, therefore, will not keep long, as it absorbs oxygen from the air, or sticks together with the coating of the stencil sheet due to the presence of resins which react with the oleaginous materials.

The backing sheet, according to this invention, has a coating chiefly of non-drying oil, it has a grease-proofing quality and is very stable, so that it will keep a long time. Moreover, it does not become hard and brittle as in the case where drying oils or varnishes are used, and does not stick to the surface of a stencil sheet.

In the practice of the invention a firm stifl,

. paper, such as manila paper, is coated on one or both sides with a coating material composed largely of non-drying oil, e. g., castor oil, and if desired a hardening material, e. g., as carnauba wax, Montan Wax, bees wax, copal, ester gum, or a mixture of these the substances being previously dissolved in a suitable solvent such as turpentine oil, benzol, petroleum benzine or a mixture of them. And then the coated sheet after the evaporationof the volatile matter may be calendered through hot rollers.

By way of illustration, although the proportions of the ingredients of the coating material may vary according to circumstances,.an example is given as follows:

Example Parts by weight Castor oil 90 Carnauba wax 5 Copal 5 Turpentine oil 100 Benzol 200 Petroleum benzine 100 v the present invention, the backing sheet being stifli, firm and greaseroof only serves as a protection against t e dissipation ofv the oils contained in the coating of the socalled dry-process stencil sheet which does not require any moistening, but it produces even and clear characters on the stencil sheet. Turkey-red oil is a salt of sulphonated 5 glycendes of fatty acids, and therefore, is

not included in the present invention.

The stencil sheet is su erimposed upon the backing sheet and the ormer may be attached'at one end to the latter as in the usual In the stencll-cuttmg operation, the combined stencil and backing sheet is introduced into the typewriting machine and the characters are produced on the stencil sheet by the impact of the type of the machine, or the sheet may be stencilized by the pressure of a hand stylus in the usual manner. It 1 results in a sharply defined clear copy. It is more convenient to insert a sheet of thin paper, or cloth, immediately between the stencil sheet and the backing sheet for the sake of producing even characters on the stencil sheet.

,What I claim is 1. A backing sheet for a dry-process stencil sheet conslsting of a firm stifi' paper treatedwith a coating composition including a non-drying oil and a hardening material for the purposes described.

2. A backin sheet for a dry-process stenoil sheet consisting of a firm stiff paper treated with a coating composition including a non-drying oil waxes and resins for the purpose describe In testimony whereof I afiix my si -nature.

SHINJIRO 1161111. 

